OK,… to move on and display some progress I guess it’s a sand pit we need to build soon. Kids stuff to some.
Diary: Thursday 14th of March 2002
Just as well SSL crawls to the sea early a.m. and are to be seen. But what about mid-month when high tide is around Sunset because that leaves them all the leisure time in the world to follow the tide out in the dark, in peace. (no predators to concern themselves with- bar hedgehogs or strolling folk at night. Perhaps the odd rat too) Yes, that’s the best time for ’em. Wonder if possums eat them.
To come back home to the dunes – the optimum time must be a low tide at Sunset, which effectively gives them around six hours of ‘blackout’ bliss. Have observed them active half an hour before Sunset. I wonder what they go by. Do they rely on their internal biological clock or use magnetic bearings. Do they sense light as we perceive it- or are sensitive to polarised light as is the isopod Scyphax ornatus? ( See Mike Bradstock’s excellent book- ‘Between The Tides.’)
What part does the Moon play in all this. Are all these requirements necessary. And when they are dug in at the low tide, does water pressure as the tide sweeps over them play a part and so ‘adjust their clocks’, or assist in whatever it is they are up to. Or the sound of the sea, what part could that play. They more than likely hear or feel the slightest ripples. Does the sea water’s pressure as the tide comes up the beach forcibly accomplish necessary biological changes in some peculiar fashion. Do they need to absorb salt or nutrients by way of micro organisms from the sea and sand. Are they absorbing through their skin or ingesting something orally. How long is the submersion period. Is this a pre-Winter annual occurrence. Does it occur in perhaps only the final instar year. As the Sand Scarab Larvae live for more than one year, is it obligatory every year of their lives to perform this, or perhaps only the last year prior to pupating in the sand dunes.’
One could sit and ponder on these marine migratory habits for some time.